The present invention deals with the field of signal modification. In particular, it deals with a method and device/s for the selection of frequency portions of at least two versions of a signal which are summed to create a signal which may be superior to, and/or avoid problems found in, one or more of the source signals.
When transducing audio signals to electrical signals, it is common to eliminate undesireable elements by the process of somehow filtering or equalizing those signals. For example, where a musical performance is recorded in a concert hall, problem noises are often caused by the noises made by lights, HVAC systems and blowers, etc. Some of these sounds may be more pronounced at some places than at others. It is common for there to be certain places where the overall sound is most desireable, even though such places may have specific problems, such as a particular buzz caused by a nearby light fixture. When a placement still seems optimum despite a problem, the common solution is to use a filter/equalizer to reduce the frequency band of the offending sound. The filter reduces all signal in the given frequency band, both the offending sound and the desired portions of the signal. In the circumstance where there is no desired signal in the given frequency band, this is not a problem. An example is when there is an undesireable high-pitched hiss as commonly given off by a steam radiator, and a person at a podium talking into a microphone. There is a good chance that there is little energy from the person that is in the frequency range of the hiss, so reducing that range drastically to reduce the offending hiss will not degrade the intelligiblity of the person.
However, if the steam radiator is sharing the room with a group of musical instruments, such as a chamber orchestra, certain elements of the music will be affected. Higher notes or instruments (such as flutes) may be affected more than others, thus changing the balance of notes and instruments from what the composer intended and the performers practiced. A sound engineer will seek to affect the musical sound as little as possible while eliminating the offending sound as much as possible. The typical result is a compromise where there is more of the offensive sound than desired, the music does not sound as good as it could, or both.